[Popular Sites] Add Variations parameter to override URL path

components/ntp_tiles/popular_sites.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_NTP_TILES_POPULAR_SITES_H_
 #define COMPONENTS_NTP_TILES_POPULAR_SITES_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 48 matching lines @@
   // Must be called at most once on a given PopularSites object.
   virtual bool MaybeStartFetch(bool force_download,
                                const FinishedCallback& callback) = 0;
 
   // Returns the list of available sites.
   virtual const SitesVector& sites() const = 0;
 
   // Various internals exposed publicly for diagnostic pages only.
   virtual GURL GetLastURLFetched() const = 0;
   virtual GURL GetURLToFetch() = 0;
+  virtual std::string GetDirectoryToFetch() = 0;
   virtual std::string GetCountryToFetch() = 0;
   virtual std::string GetVersionToFetch() = 0;
   virtual const base::ListValue* GetCachedJson() = 0;
 };
 
 }  // namespace ntp_tiles
 
 #endif  // COMPONENTS_NTP_TILES_POPULAR_SITES_H_